AEW541, also known as NVP-AEW541, is a novel, potent IGF-IR kinase inhibitor. NVP-AEW541 is capable of distinguishing between the IGF-IR (IC50 = 0.086 microM) and the closely related InsR (IC50 = 2.3 microM) in cells. NVP-AEW541 abrogates IGF-I-mediated survival and colony formation in soft agar at concentrations that are consistent with inhibition of IGF-IR autophosphorylation. NVP-AEW541 represents a class of selective, small molecule IGF-IR kinase inhibitors with proven in vivo antitumor activity and potential therapeutic application.